Problem: In October 2009, Science published a series of articles in a special issue describing a new hominid species, Ardipithecus ramidus, that took many years and an international team of scientists to analyze. Read the one page overview description (p.65) and reference the subsequent article about the archaeological context of this fossil and its environment. Explain the concept of marker beds, index fossils, potassium-argon and argon-argon dating using examples from African site.